Download Cells, tissues and organs

National 5 Biology
Unit 2
Multi-cellular
Organisms
Name: ___________________________________________
Class:
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1
Cells, tissues and organs
Cells Tissues  Organs  Systems  Organism
Learning Intentions
 I can explain what is meant by the term ‘specialisation of cells in animals and plants’.
 I can give details of how the structure of an animal cell or plant cell can relate to its function.
 I can state that the cells in organs are specialised for a specific function.
 I can describe the levels of organisation found in animals and plants.
Specialised cells
Plants and animals are multi-cellular organisms as they have more than one type of cell. Each
type of cell is designed to carry out a particular job or function. This is known as cell
specialisation.
Examples
Sperm Cell
Tissue
Head
contains
enzymes &
nucleus
Root Hair Cell
Cell type
Red Blood Cell
Function
T
ai
l
 Cells of one type group together in the body to form tissues. For example, muscle tissue is
made up of only muscle cells.
 Organs are made up of different tissues working together to carry out a specific job. An
organ can contain different types of tissue. For example, the heart is made up of muscle
tissue, blood tissue and nervous tissue (nerves).
 Each tissue is made up of specialised cells that allow each tissue and subsequently each
organ to carry out a specialised job.
 Organ systems are made up of two or more organs that work together to provide a common
function e.g. Nervous system, circulatory system, reproductive system etc.
Stem Cells and Meristems
Learning Intentions
 I can state that stem cells have the ability to divide to produce cells that can become
different types of cells.
 I can state that stem cells are involved in growth and repair.
 I can describe the role of meristems in plants.
 I can state that non-specialised cells can become any type of plants cell and they contribute
to growth.
Stem cells
Stem cells are unspecialised cells that have the potential to divide and make more stem cells
by mitosis or to become another type of cell with specialised function.
In early development embryos are composed of stem cells. This allows the embryo to develop all
the different parts of the body and the different cell types needed to form a fully functional body.
Through embryonic and foetal development the number of stem cells steadily decreases until very
few stem cells remain.
Production of blood cells.
Blood contains red and white blood cells that are repeatedly replaced by new blood cells
produced by stem cells. These stem cells are found in red bone marrow- found inside bones.
Uses of stem cells in medicine
Stem cells can be cultured (grown) in laboratories. These cells have huge medical potential, as
they can become any type of specialised cell.
Research scientists hope to develop methods that could use stem cells to replace diseased or
worn out parts of tissue with new, healthy tissue. For example, repairing damaged heart tissue;
treat diabetes; or to reverse Parkinson’s disease and Alzheimer’s disease.
Embryonic stem cells Vs. Adult stem cells
Stem cells have been used in medicine for many years – bone marrow transplantation is a form of
stem cell therapy using adult stem cells. However, adult stem cells can only form a limited range
of specialised cells. Embryonic stem cells can have the potential to make any body cell.
Ethical Issues
Objections
 Human life should never be created as a means to an end.
 Catholic Church hold the belief that new life begins at the moment of conception and
embryos should have full human rights.
 Use of embryonic stem cells is not justified when other sources of stem cells are available
Researchers argue that it is still not clear which types of stem cells will prove the best
therapeutically. A balance has to be found between the rights of the embryo against the
potentially large benefits that others may gain from research and ultimately stem cell based
treatments.
Meristems
In animals, growth can occur all over the body. In plants, growth is restricted to special points call
meristems. These regions contain stem cells. The cells at a meristem are constantly dividing
by mitosis to form more meristemic cells or cells which can elongate and develop into specialised
cells and tissues in the plant.
Meristemic cells have the potential to become any type of cell in the
plant.
These are found at the root and shoot tips. They cause an increase in
the height of the plant and length of the roots.
Control and Communication
Learning Intentions
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I can describe the structure of the brain.
I can give details of the functions of the different structures of the brain.
I can describe the structure and function of the central nervous system (CNS).
I can state that the CNS is the communication system.
I can describe the role of sensory and motor neurons.
I can explain the role of sensory, relay and motor neurons in a reflex arc.
I can state that electrical impulses move along neurons.
I can explain the importance of synapses in the nervous system.
I can describe the different responses brought about by the CNS.
I can explain what a reflex action is and give some examples.
I can explain the importance of reflex actions.
I can state the function of endocrine glands.
I can describe the role of hormones in signalling.
I can describe the role of the liver, pancreas, insulin and glucagons in controlling blood glucose
levels.
 I can state that glucose can be stored as glycogen in the liver.
 I can describe the causes and treatment of type 1 and type 2 diabetes.
 I can explain the importance of controlling blood glucose levels.
The Brain
The brain is the most complex organ in your body. It is protected by the skull and controls the vital
processes that occur in your body, keeping you alive.
Try and make a way to remember he difference between the location and functions of the
Cerebrum and Cerebellum.
The Nervous System.
In humans, the nervous system is composed of the brain, spinal cord and nerves.
The central nervous system (CNS) is made up of the brain and spinal cord.
The central nervous system sorts information from the senses and sends messages to muscles
and other parts of the body to stimulate the appropriate response.
Neurones are specialized cells of the nervous system that conduct electrical impulses through the
body, to and from the CNS.
A neuron consists of a cell body attached to nerve fibres. An electrical impulse is carried towards
the cell body of a neuron by a sensory fibre and away from it by an axon fibre.
The fatty myelin sheath acts as insulation and speeds up the
impulse.
Reflex Arc
Sense organs contain receptor cells which detect stimuli (changes in the conditions). This
information is passed along sensory neurones to the CNS. The CNS processes the information
and brings about the responses. Responses are passed from the relay neuron then along motor
neurons to the effectors. An effector may be a muscle that brings about a rapid response.
Stimulusreceptorsensory neuronrelay neuronmotor neuroneffectorresponse
Synapse
A tiny space called a synapse occurs between the axon ending
of one neuron and the sensory fibre of the next. When a nerve
impulse arrives, the ending of the axon branch releases a
chemical. This diffuses across the space between the two
neurons and triggers off an impulse in the sensory fibre of the
next neuron.
Sensory fibres
Reflex actions
The transmission of a nerve impulse through a reflex arc results in a reflex action. This is a rapid,
automatic, involuntary response to a stimulus. When the flame
(stimulus) comes in contact with the hand, the pain receptors
send an electrical impulse up the sensory neuron, through the
relay neuron in the spinal cord, to the motor neuron to the arm
muscle (effector) to move the arm away from the harm
(response) and drop the burning match.
Reflex actions protect the body from damage.
Some examples of reflex actions in humans include:
Hormonal Control of the body
As well as using the nervous system to control and coordinate the
body, hormones play a similar role in keeping your body working.
Hormones are chemical messengers (made of protein) which
are made by the endocrine glands in the body and travel in the
blood to specific target tissues. When the hormone arrives at its
target tissue the specific receptors in the tissue detect the
hormone and initiating a response.
Make notes on-Roles of hormones in the human body-P89
These are glands
which are part of
the endocrine
system
Osmoregulation in the human body
It is important to regulate blood water concentration so that cells have the right water
concentration.
 Monitoring centre – Hypothalamus
(osmoreceptors)
 Control Centre – Pituitary gland
 Hormonal message – ADH
 Effector tissue – Kidney
Homeostatic control of blood water concentration
Blood Glucose Regulation
All living cells in the human body need a continuous supply of
energy.
Most of the energy required by cells is gained through the
breakdown of glucose during aerobic respiration.
Glucose concentrations in the blood must be kept within
tolerable limits and involves the following:
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Monitoring centre – Receptor cells in Pancreas
Control Centre – Pancreas
Hormonal message – Insulin or Glucagon
Effector tissue – Liver
Insulin causes the liver to convert glucose  glycogen (a storage carbohydrate) and therefore
reduces the levels of glucose in the blood.
Glucagon causes the liver to convert the storage carbohydrate glycogen  glucose and therefore
increases the levels of glucose in the blood.
The system described above is an example of negative feedback since the corrective mechanism
opposes the existing trend and then switches off when blood glucose levels return to normal.
During an emergency the adrenal gland secretes the hormone adrenaline into the bloodstream
Adrenaline overrides the normal homeostatic mechanism by inhibiting the secretion of insulin and
promoting the breakdown of glycogen to glucose. This raises the levels of glucose and allows the
body to produce energy for ‘flight or fight’. Once the emergency is over the levels of adrenaline
drop and allow normal homeostatic control mechanisms to take over.
Diabetes
People who suffer from diabetes are unable to control their blood glucose levels. Diabetes is the
result of a communication pathway that has broken down.
Research the following: the consequences, treatment, causes and the two different types. Make a
summary of these findings here.
Additional notes
Reproduction
Learning Intentions
 I can describe the chromosome complement of gametes.
 I can describe the structure if the male and female sex cells and state where they are
produced.
 I can give details of the male and female reproductive structures, including their function.
 I can describe the process of fertilisation in animals.
 I can give details of the chromosome complement of a gamete and zygotes in animals.
 I can name the sex cells found in plants and state where they are produced.
 I can describe the reproductive structures found in plants and give their functions.
 I can describe the process of fertilisation in plants.
 I can give details of the chromosome complement of a gamete and zygotes in plants.
Sexual reproduction
Reproduction must take place in all species to produce offspring and maintain population
numbers. Sexual reproduction in animals involves two parents.
Animal Reproduction
Gamete production
Gamete
Number
produced
Relative
Size
Important structures and functions
Diagram
Sperm
Egg (ova)
 In each diagram below highlight the site of gamete production (the gonads).
Male reproductive system
Female reproductive system
Structure
Male
Testes
Penis
Urethra
Sperm duct
Female
Ovary
Oviduct(fallopian tube)
Uterus
Vagina
Cervix
Fertilisation
Every month the female will release an egg from the
ovary (Ovulation). Cilia beat the egg down the oviducts
towards the uterus. If sexual intercourse has taken place
and sperm have been deposited into the female’s vagina
they will swim up the uterus and into the oviducts.
It is here in an oviduct that fertilisation takes place.
Stages of development
Egg + Sperm  Zygote  Embryo  Foetus  Baby
Function
Plant reproduction
Flowers are the organ in which sexual reproduction takes place in plants.
 Highlight in the diagram where gamete formation occurs.
Structure
Function
Sepal
Protects unopened flower
Petal
Brightly coloured to attract insects
Anther
Produces pollen
Pollen
Contains male nucleus
Stigma
Where pollen lands
Ovary
Contains ovule
Ovule
Contains female nucleus
Nectary
Produces nectar to attract insects
Nectar is sugary water
Gametes in flowering plants
Male-Pollen grains
Female –ovule in the ovary
Pollination
This is the process of transferring pollen grains (male) from the anther to the stigma of the flower.
This can by wind of insect transfer.
Growth of a pollen tube
Step 1- The pollen grain has landed on the sticky sugary stigma which initiates
the pollen tube to grow.
Step 2- The pollen tube grows down the style, into the ovary and into the ovule.
Step 3- The male nucleus will travel down the pollen tube to meet with the
ovule nucleus where fertilisation will take place.
Fertilisation
This is the process when the nucleus of the pollen grain (haploid) fuses with the
nucleus of an ovule (haploid) to produce the zygote (diploid) which will become
the seed.
The ovary will grow into a fruit containing the seed and after dispersal the seed
will grow into a new plant.
Variation and Inheritance
Learning Intentions
 To develop knowledge on inheritance
 To be able to describe and explain the difference between continuous and discrete
variation.
 To know the biological terms of genetics and inheritance. Such as phenotype, dominant,
recessive and true breeding and identify examples from given crosses
 To be able to use a punnet square to carry out a Monohybrid cross.
 To develop knowledge on polygenic inheritance.
 To develop understanding on family trees and the benefits they have.
Fertilisation is the fusion of the two haploid nuclei of the gametes to form a diploid zygote.
Fertilisation is a random process. The zygote ends up with half its genetic complement from
each parent. This is how characteristics are passed down through generations. THIS IS CALLED
INHERITANCE.
Variation
There are two types of characteristics that are inherited from parents;
1) Discrete (Discontinuous) Variations= Characteristics with distinct categories e.g.
……………………………………………………………….
2) Continuous Variations= A characteristic which increases or decreases in a regular way e.g.
………………………………………………………………
Continuous variation can also be described as Polygenic.
The following terminology is used to describe inheritance.
Gametes
Genotype
Phenotype
Alleles
Dominant
True breeding
Heterozygous
Polygenic
Monohybrid Cross
True Breeding Example
There is a standard way to set out a genetic cross, as shown below.
Observed vs Predicted Ratios
Punnet squares give a predicted ratio. We predict a ratio of 3:1, for the above cross between two
true breeding (homozygous) mice however we rarely get this in practise.
This is because: Fertilisation is random and involves the element of chance.
Family tree
A family tree is a diagram showing the relationships between people in several generations of a
family.
Family trees can be used to identify individuals with a genetic condition.
A genetic condition is an illness caused by abnormalities in genes or chromosomes. For e.g.
……………………………………………………………
Genetic counselling is the process by which patients or relatives, at risk of an inherited disorder,
are advised of the consequences and nature of the disorder, the probability of developing or
transmitting it, and the options open to them in management and family planning.
Transport Systems
Plant Transport Systems
Learning Intentions
 To understand why multi-cellular organisms need transport systems.
 To understand the function of a leaf in transport systems of a plant
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To know the structures involved in transport of water and food around a plant
To understand the functions of transpiration in a plant
To describe the process of transpiration
To state the effects of environmental conditions on transpiration and how to measure this effect
The need for transport mechanisms in multi-cellular organisms
Single celled organisms do not need transport systems. They are so small that substances can
move in and out of them by diffusion.
Multi-cellular organisms with several or many layers of cells and which are more active need
specialised exchange and transport systems.
Diffusion would take place too slowly to supply the organism with what it needs.
Leaves
Photosynthesis occurs in the leaves of green plants.
Functions of the Parts of a Leaf
Structure
Feature
Function
Cuticle
Waxy layer
Epidermis
Close fitting cells
Mesophyll
Contain many chloroplasts
Protects
Tubes made from xylem and
Vein
phloem
Guard cell
Changes shape
Stoma
Pore
Structure of Stoma
guard cell
chloroplast
thick inner part
of cell wall
stoma pore
Closed
thin outer part
of cell wall
Open
Stomatal Movements
Stomatal opening and closing is dependent on changes in turgor in the guard cells.
Stomatal opening
When water enters a pair of guard cells they become turgid/flaccid. The thin outer cell walls
stretch more than the thick inner walls, this causes the two guard cells to bulge out and the stoma
pore to open/close as the thick inner walls are pulled apart. Stomata usually open during
daylight/darkness; this lets carbon dioxide enter the leaf and allows water loss by transpiration.
Stomatal closing
When water leaves the guard cells, they become turgid/flaccid. The guard cells no longer bulge
outwards and the pore closes. This usually occurs during daylight/darkness and will conserve
water at night.
Plant Transport Structures
Plants have two transport systems to move
• Water and minerals upwards from the roots – XYLEM.
• Sugar to all parts of the plant (translocation) – PHLOEM.
Structure of Xylem
Xylem is dead tissue.
- The xylem has hollow tubes to allow the
Hollow tube
Spiral of lignin
movement of water.
- The rings of lignin provide support.
Structure of phloem
Phloem is living tissue.
Made of two types of cell,
- Sieve tubes and Companion cells
- Sieve tubes - transport sugar.
- Companion cells - control both types of cell.
- Sieve plates - allow rapid transport of
Sieve
tube
- Strands of cytoplasm - help move sugar
Sieve plate
sugar
Nucleus
from one sieve tube to another.
Companion
cell
Cytoplasm
strands
Diagram of a root cross section to show xylem and phloem
Diagram of a stem cross section to show xylem and phloem.
Transpiration
Roots
All plant cells need water for many processes. Green plant cells need water for photosynthesis. The
roots take up water they have a large surface area to allow the plants to take up sufficient water. Root
hairs are single cells that greatly increase the surface area of the root allowing the plant to take in large
amounts of water and minerals. Water is taken in to the root hairs by osmosis.
Transpiration
The loss of water by evaporation from the leaves of a plant is called transpiration.
The resulting flow of water through the plant is called the transpiration stream.
Importance of the Transpiration Stream
The transpiration stream is important because:•
•
•
•
it carries water for photosynthesis to the cells in the leaves.
the water carries essential minerals in solution
evaporation from the leaves has a cooling effect.
the water maintains turgor in cells to give the plant structure
Plants play an important role in the water cycle, moving water from the soil into the atmosphere.
Water evaporates (transpiration)
mostly through holes in the leaf - stomata
Causing water to be drawn in from the ste
Transpiration
causes continuous thin columns of water to be
drawn up the stem
Water enters the xylem in the stem
Water moves across the root towards the centre
Root hair
Greatly increases the surface area for absorption
Water and minerals in soil
enter the root
Measuring Transpiration
Transpiration rate can be measured by using a weight or a bubble potometer.
The weight potometer allows the calculation of weight of water lost per unit time.
Water loss in a leafy twig under normal conditions
The weight potometer measures
The bubble potometer allows the calculation of the rate of water uptake per unit time.
Both potometers allow comparison of transpiration under different conditions.
Conditions Affecting Transpiration
Any abiotic factor that affects evaporation rate will affect the rate of Transpiration.
Factor
Effect on Transpiration Rate
Temperature increase
Temperature decrease
Windspeed increase
Humidity increase
Light intensity
Torrance Higher textbook page 184 questions 1 and 3.
Animal Transport Systems
Learning Intentions
 To understand why multi-cellular organisms need transport systems
 To have knowledge of the organs involved in animal transport systems
 To label a heart and describe the flow of blood around the heart
 To know the names and structures of the vessels involved in transporting blood around the
body
 To know the constituents of blood and their functions
 To label the structures of the lung and understand their role in transport of gases.
 To understand the need for digestion
 To know the organs of the alimentary canal and their role in digestion
 To know what happens to the final products of digestion
Circulation and the Heart
The human heart is a simple but very efficient _____________ beating over 100,000 times a day.
The four chambers, four valves and various blood vessels transport _____________ into and out
of the heart. The heart is a double muscular pump - one side pumps blood around the body, the
other to the lungs. Blood carries soluble food, gases, waste and hormones. Blood flows twice
through the heart for each circuit.
The wall of the left ventricle of the heart is thicker than the wall of the right ventricle
because……………………………………………………………....
The function of the valves is to stop the back flow of blood in the heart.
The heart muscle itself obtains a blood supply from the coronary artery. If it gets blocked then;
Blood Vessels
There are three types of blood vessel;
Artery
Notes
Arteries (away from the heart)
Veins (towards the heart)
Capillaries (between arteries and veins)
Vein
Capillary
Heart Dissection Observations
a) The hard cream coloured tissue on the surface of the heart is
b) The colour of the tissue which makes up the walls of the heart is
c) The wall of the left ventricle is ________ times thicker than of the right ventricle
d) The coronary blood vessels are ________________________________
e) The blood vessel with the thickest wall is the ________
f) The type of blood vessel that has an elastic wall is ________________
g) Heart valves are ________________________
h) The heart valves are held open by ________________
Blood
Blood is made up of several components. Complete the table showing the functions of the parts of
the blood.
Name of blood component
Drawing of component
structure
Function of cell component
Transports oxygen around
the body
N/A
Platelets
Yellow fluid that contains the
blood cells, glucose and CO2
Clotting blood, forming
scabs, stopping bleeding
Red blood cells contain haemoglobin which traps oxygen and creates oxyhaemoglobin for
transportation around the body.
a) Where, in the body, does haemoglobin become oxyhaemoglobin?
b) Which type of cell will kill a cell that is infected with a virus?
c) People who suffer from haemophilia bruise very quickly and cannot stop bleeding when cut.
What component of blood is not working properly?
d) Which famous family has haemophilia in its genes?
e) Which gas, excreted by cells, is carried by the plasma to the lungs?
The Lungs
Lungs are designed to be efficient at gas exchange. They are composed of many tubes, each
ending in microscopic air sacs called alveoli. Air passes from the mouth to alveoli.
The Alveoli
Air sacs are found at the end of bronchioles.
They are the site of gas exchange in the
lungs. Air sacs are lined with mucus and are
surrounded by blood capillaries.
The air sacs have a very large total surface
area and a very good blood supply.
Why are these things important?
Feature
Large surface area
Moist
Thin walls
Rich blood supply
Importance
Mucus and Cilia
Mucus also lines the trachea and bronchi – this sticky mucus traps any dust and micro-organisms
which are breathed in.
The cells that line the air tubes (trachea and bronchi) are covered in tiny hairs called cilia. They
move back and forth to sweep the mucus upwards towards the throat. This helps to remove the
dust and micro-organisms trapped by the mucus (the mucus is usually swallowed)
Digestion
The purpose of digestion is to breakdown large insoluble particles of food, to small soluble
particles.
Allows food to be absorbed into the blood and transported to the cells. The main dietary
components required by the body can be found in the table below.
Food Group
(Large Insoluble
Food Molecule)
Starch
Protein
Fat
Constituent
Elements
Basic Unit
(Small Soluble
Food Molecule)
Contained Within
The Model Gut
The process of absorption can be demonstrated with a model gut.
Starch is a large molecule made up of many small glucose molecules joined together.
The starch glucose mixture represents …………………..
The water represents …………………………….
The visking tubing represents ……………………………….
What can we conclude about this experiment?
The Alimentary Canal
A long muscular tube that runs from the mouth to the anus. The digestive system has a number of
organs attached to it. These add fluids to speed up the breakdown of food.
Part of Digestive
Tract
Mouth
Oesophagus
Stomach
Small Intestine
Large Intestine
Rectum
Function
Label the diagram of the Alimentary Canal.
Peristalsis is the muscular contraction and relaxation of the wall of the alimentary canal to push
food along.
The Stomach
What is the purpose of the following cells?
Mucus Secreting Cell –
Acid Secreting Cell Enzyme Secreting Cell -
There are several organs that are associated with the Alimentary canal that have a role in
digestion. These are called Associated Organs.
Pancreas Liver Gall Bladder –
Digestive Fluids
The many organs of the digestive tract produce a variety of digestive fluids containing digestive
enzymes, as detailed in the following table.
The Small Intestine
The small intestine’s function is to absorb soluble food molecules and it is well suited to this job in
a number of ways.
- It is very long (About 6m). The inner surface is folded.
- Each fold has thousands of finger-like villi to increase the surface area.
- The lining of each villus is very thin. (Only one cell thick)
- Each villus has a network of vessels for absorbing the food, both blood capillaries and lymphatic
vessels. (Lacteals)
The Villus
Indicate on the diagram where glucose, fatty acids, glycerol and amino acids are absorbed.
What are the benefits of the following?
-
a thin wall
a good blood supply
lacteal
Fate of Absorbed Materials
 The glucose and the amino acids are absorbed into the blood capillaries, by the process of
diffusion.
 These tiny blood capillaries all join up to form the hepatic portal vein and transport the
absorbed food to the liver.
 The liver stores most of the glucose as glycogen until it is required, but some glucose
remains in the blood.
 The amino acids are used in the body for growth and repair, but if there are any excess
amino acids, these are broken down by the liver into urea.
 This is later removed by the kidneys and released in the urine. Fats and fatty acids are
absorbed by the lacteals which contain fluid called lymph.
 This lymph is transported in the lymph vessels which will eventually drain into the blood
system.
Lifestyle Choices
Learning Intentions
 To understand the effects of lifestyle choices on animals transport and exchange
systems
 To be able to identify that certain lifestyle choices can have a negative impact on peoples’
health.
 To be able to identify that certain lifestyle choices can have a positive impact on your health
 To identify the health risks individuals have with certain lifestyle choices.
 To investigate how exercise will affect an animals transport and exchange mechanisms
 To understand the need for vaccinations
 To debate the need for free NHS treatments for all diseases.
Lifestyle Choices
In your jotter make notes on the effects of the following lifestyle choices;
High Fat
Low Nutrient Diet
High Salt
Lack of Exercise
Stress
Smoking
Alcohol
Effects of Lifestyle Choices
Bear in mind that some of these may not be due to lifestyle choice alone but can be linked to
genes also, this means they are Hereditary.
Vaccinations
Vaccines help to protect us against infectious disease. There are many issues surrounding the use
of vaccines. Use the space below to detail some of these issues after discussion in class.
Notes